In numerous installations, a water pump and the electric motor which operates the water pump are submerged within the body of water from which water is pumped. In other water pump installations, a water pump and an electric driving motor may be located a considerable distance from the electric control unit which supplies electrical energy to the electric motor. In each water pump installation, there is a possibility that the supply of water at the pump may cease or a coupling between the driving electric motor and the water pump may break, or for some other reason the electric motor operates without pumping operation of the water pump. If the supply of water to the water pump ceases, the pump may be severely damaged if it is operated. If the coupling between the electric motor breaks or for some other reason the pump is operated without pumping action, a signal should be provided in regard to such a condition, and/or the motor should be deenergized.
Numerous types of water pump protector devices and indicator or signal circuits have been devised. Most of the pump protector devices require a separate mechanism to sense the water level condition and to provide a signal for manual or automatic deenergization of the electric driving motor. However, such devices require a separate electric circuit which extends from the body of water to the electric motor control unit. In most installations, the distances between the body of water and the electric motor control unit may be considerable and require long lengths of electric wire, as well as requiring a separate mechanism at the water level or in the body of water. Therefore, such protective devices have disadvantages. Pump protective or pump malfunction indicator devices and circuits which do not require separate mechanisms or circuits are usually complex and costly and are therefore objectionable.
It is an object of this invention to provide electrical circuitry through which electrical energy is supplied to an electric motor which operates a liquid pump and in which the electrical circuitry deenergizes the electric motor if, for any reason, the liquid pump is not pumping liquid. Thus, it is an object of this invention to provide electrical circuitry which protects the liquid pump against damage and which may also serve as an indicator that the electric motor is operating without pumping action in the pump.
It is another object of this invention to provide such electrical circuitry which is relatively low in cost to produce and to install.
Other objects and advantages of this invention reside in the construction of parts, the combination thereof, the method of production, and the mode of operation, as will become more apparent from the following description.